Earnings Per Share (Narrative) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Line Items]
Computation of earnings per share, methodology	Basic earnings per share is computed by dividing earnings available to MasTec’s common shareholders by the weighted average number of common shares outstanding for the period. Diluted earnings per share is computed by dividing earnings by the number of fully diluted shares, which includes the effect of dilutive potential issuances of common shares as determined using earnings from continuing operations. The potential issuance of common shares upon the exercise, conversion or vesting of outstanding stock options and unvested restricted share awards, as calculated under the treasury stock method, as well as shares associated with the Company’s outstanding convertible debt securities, may be dilutive.
Treasury stock acquired, shares		4.9
Treasury stock acquired, value		$ 75.0
Unsecured Debt [Member] \| Convertible Debt [Member]
Earnings Per Share [Line Items]
Computation of earnings per share, methodology	Dilutive shares associated with the 2009 Convertible Notes are attributable to the underlying principal amounts. As the Company’s weighted average stock price for the three and nine month periods ended September 30, 2013 and 2012 exceeded the conversion prices of the 2011 Convertible Notes, dilutive shares associated with the 2011 Convertible Notes, which are attributable to the weighted average premium value, in shares, of the conversion shares underlying the 2011 Convertible Notes in excess of the respective principal amounts thereof, have been included in the Company's share count for the corresponding periods.
Unsecured Debt [Member] \| Convertible Debt [Member] \| Total Convertible Debt [Member]
Earnings Per Share [Line Items]
Principal amount	215.0
Unsecured Debt [Member] \| Convertible Debt [Member] \| 2011 Senior Convertible Notes [Member]
Earnings Per Share [Line Items]
Principal amount	202.3
Unsecured Debt [Member] \| Convertible Debt [Member] \| 2009 Senior Convertible Notes [Member]
Earnings Per Share [Line Items]
Principal amount	12.6
Unsecured Debt [Member] \| Convertible Debt [Member] \| 2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Principal amount	105.3
Debt instrument, interest rate	4.00%
Conversion price per share	$ 15.76
Unsecured Debt [Member] \| Convertible Debt [Member] \| 2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Principal amount	$ 97.0
Debt instrument, interest rate	4.25%
Conversion price per share	$ 15.48

The price per share of the conversion feature embedded in the debt instrument.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Disclosure of the methodology and assumptions used in the reconciliation of earnings per share, which may include the individual income and share amount effects of all securities that affect earnings per share, the effect that has been given to preferred dividends in arriving at income available to common stockholders in computing basic earnings per share, securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic EPS in the future that were not included in the computation of diluted EPS because to do so would have been antidilutive for the period(s) presented and a description of any transaction that occurs after the end of the most recent period but before issuance of the financial statements that would have changed materially the number of common shares or potential common shares outstanding at the end of the period if the transaction had occurred before the end of the period.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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